不同改良措施对退化草原土壤碳、氮储量的影响

Effects of Different Measures for Improving Degraded Grassland on the Soil Carbon and Nitrogen Stocks in Steppe of Inner Mongolia

对围栏封育、浅耕翻和耙地改良24年后的退化草原的土壤碳、氮储量测定表明：（1）不同措施对土壤有机碳含量的影响是：在L1层（0~10cm）自然恢复和耙地改良显著高于浅耕翻改良和围栏外放牧;L2（10~30cm）层自然恢复显著高于耙地改良;浅耕翻改良显著高于围栏外放牧。（2）土壤有机碳储量在L1层自然恢复、耙地改良显著高于围栏外放牧、浅耕翻改良;在L2层自然恢复显著高于耙地改良;浅耕翻改良显著高于围栏外放牧。（3）L1层全氮含量、全氮储量均表现出自然恢复、耙地改良显著高于浅耕翻改良,三者均显著高于围栏外放牧;L2层全氮含量、全氮储量表现出三种恢复改良措施改良后显著高于围栏外放牧。（4）三种改良措施都有利于土壤C、N的积累,且在中等时间尺度上随着改良干扰程度的加重积累量相对减少。（5）不同措施对退化草地恢复的效果不同,依据恢复目的有针对性的选择不同措施是十分必要的。

The enclosure,shallow plough and harrowing were used to improve degraded steppe in central Inner Mongolia.The long term effects of these measures on the soil organic carbon（SOC）and nitrogen（SON）stocks were determined in 24 years after the application of these measures.The results showed that：（1）SOC content in top soil layer（L1：0~10cm）in the enclosure and under harrowing were higher than that under shallow plough and animal grazing;in the layer L2（10~30cm）,SOC content was higher in the enclosure than under harrowing and shallow plough,which were higher than that under animal grazing.（2）The SOC stocks in L1 was higher under natural restoration（enclosure）and harrowing than that under shallow plough and animal grazing;and in L2,SOC was higher in enclosure than under harrowing and shallow plough,which were higher than animal grazing.（3）The SON contents and stocks in L1 were higher under natural restoration（enclosure）and harrowing than under shallow plough and animal grazing;and the SON contents and stocks in L2 were higher under all improving measures than animal grazing.（4）All improving measures were beneficial to the SOC and SON,but the accumulation decreased with the increasing of the disturbance strength of these measures.（5）Different measures differed in their effects on the degraded grassland,thus it was necessary to select different measures based on the aims of restoration.